Because you can only consume so much food Optimum Nutrition have produced this weight gain formula for those people looking to pack on some serious mass. Make no mistake this is a beast of a weight gainer because a serving of this will deliver 1250 calories from 50 grams of protein and more than 250 grams of carbohydrates. The good news is there's no sugar added to the formula but there is creatine and glutamine alongside 25 vitamins and minerals. What you're getting here are high quality calories in a tasty mass building shake. Key Benefits Muscle mass gains 1250 calories per serve High value proteins Proteins contained in Serious Mass are "high bioavailability" and thus are readily deployable in your body once consumed. This product also contains those essential micronutrients needed for anabolic activity. Among these important agents are creatine monohydrate, choline, glutamine and inositol. This is the bag of good stuff you need to both pack on serious mass and smash through those heavy and intense gym sessions.